I'm currently working on connecting Perl with C++ via XS, only I'm hitting a problem when it comes to typemaps.. or lack of same.

At the moment I'm handling C++'s method overloading with something with the following basic structure (plus extra error checking, removed here for clarity):

int
MyClass::countItemsIn (...)
  CODE:
    if (sv_derived_from(ST(0), 'MyList')) {
      RETVAL=THIS->countItemsIn(
        *(MyList *) SvIV((SV*)SvRV(ST(0)))
      );
    } elsif (sv_derived_from(ST(0), 'MyHash')) {
      RETVAL=THIS->countItemsIn(
        *(MyHash *) SvIV((SV*)SvRV(ST(0)))
      );
    }
  OUTPUT:
    RETVAL

[download]

..now I can happily write this kind of code, but what's worrying me is "Where are the typemaps?". If I were to do all of the conversions manually I'm a lot more likely to make mistakes, and basically mess it all up. I'm also considering wrapping things in a very different way so being able to change the effective mapping would be exceptionally useful.

What is the best way to approach this, is there a way to call typemap conversions as 'functions' in XS? If not, shall I wrap the XS code for the typemap conversion in a nice little method and call that?

EDIT: Changed wording slightly, this doesn't seem to be the 'best' version to me at all..

In reply to Terrible Trouble With Typemaps (XS Question) by Molt

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